CN114446660A - Multilayer capacitor - Google Patents

Multilayer capacitor Download PDF

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Publication number
CN114446660A
CN114446660A CN202111293389.XA CN202111293389A CN114446660A CN 114446660 A CN114446660 A CN 114446660A CN 202111293389 A CN202111293389 A CN 202111293389A CN 114446660 A CN114446660 A CN 114446660A
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CN
China
Prior art keywords
dielectric layer
core
multilayer capacitor
side edge
dielectric layers
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Pending
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CN202111293389.XA
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Chinese (zh)
Inventor
金珍友
李银贞
郑锺锡
徐春希
刘正勳
金兑炯
崔虎森
姜心忠
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Samsung Electro Mechanics Co Ltd
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Samsung Electro Mechanics Co Ltd
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Publication of CN114446660A publication Critical patent/CN114446660A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates
    • H01G4/1227—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates based on alkaline earth titanates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
    • C04B35/465—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates
    • C04B35/468—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
    • C04B35/4682—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates based on BaTiO3 perovskite phase
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/005—Electrodes
    • H01G4/012—Form of non-self-supporting electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/224—Housing; Encapsulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/228—Terminals
    • H01G4/232—Terminals electrically connecting two or more layers of a stacked or rolled capacitor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates

Abstract

The present disclosure provides a multilayer capacitor. The multilayer capacitor includes: a body including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction; and an outer electrode, wherein the body includes: an effective portion; a side edge portion covering at least one of a first surface and a second surface of the effective portion that are opposite to each other in the second direction; and a covering portion covering the effective portion in the first direction, respective dielectric layers of the plurality of dielectric layers including a barium titanate-based composition, the dielectric layer of the side edge portion including Sn, and a content of Sn in the dielectric layer of the side edge portion being different from a content of Sn in the dielectric layer of the effective portion with respect to 100 mol% of the barium titanate-based composition, and the dielectric layer of the side edge portion including at least some crystal grains having a core-shell structure.

Description

Multilayer capacitor
This application claims the benefit of priority of korean patent application No. 10-2020-0146246, filed in the korean intellectual property office on 4.11.2020, the disclosure of which is incorporated herein by reference in its entirety.
Technical Field
The present disclosure relates to a multilayer capacitor.
Background
The capacitor is an element in which electricity can be stored, and basically, when a voltage is applied to the capacitor in a state where two electrodes are disposed to face each other, electric charges are accumulated in the respective electrodes. When a Direct Current (DC) voltage is applied to the capacitor, a current flows in the capacitor while charges are accumulated in the capacitor, but when the accumulation of charges is completed, a current does not flow in the capacitor. Further, when an Alternating Current (AC) voltage is applied to the capacitor, an AC current flows in the capacitor while the polarities of the electrodes are alternated.
Such capacitors may be classified into several types of capacitors according to the type of insulator disposed between electrodes, such as an aluminum electrolytic capacitor in which electrodes are formed using aluminum and a thin oxide layer is disposed between the electrodes formed using aluminum, a tantalum capacitor using tantalum as an electrode material, a ceramic capacitor using a dielectric material having a high dielectric constant such as barium titanate between the electrodes, a multilayer ceramic capacitor (MLCC) using a ceramic having a high dielectric constant as a dielectric material disposed between the electrodes in a multilayer structure, a thin film capacitor using a polystyrene film as a dielectric material disposed between the electrodes, and the like.
Among them, since a multilayer ceramic capacitor has excellent temperature characteristics and frequency characteristics and can be realized to have a small size, it has recently been mainly used in fields such as high-frequency circuits. Recently, attempts to realize a multilayer ceramic capacitor in a smaller size have been continuously made. For this reason, the dielectric layer and the internal electrode have been formed to have a small thickness.
As a method of miniaturizing the multilayer capacitor and increasing the capacitance of the multilayer capacitor, the following methods have been used: in a step after the sheet is manufactured and before the sheet is sintered to complete the sheet, the internal electrodes are exposed in the width direction of the main body to significantly increase the area of the internal electrodes in the width direction by a rimless design, and the side edge portions are separately attached to the electrode exposed surface in the width direction of such a sheet. However, in such a method, the thickness and area of the side edge portion are reduced, and thus the risk of the side edge portion breaking and cracking due to external impact is increased. Therefore, there is a need for applying a dielectric material capable of improving impact resistance and crack resistance of side edge portions in a subminiature, high-capacitance multilayer capacitor.
Disclosure of Invention
An aspect of the present disclosure may provide a multilayer capacitor having improved electrical and mechanical characteristics by using a dielectric material having high reliability.
According to an aspect of the present disclosure, a multilayer capacitor may include: a body including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction with respective ones of the plurality of dielectric layers interposed therebetween; and an external electrode formed on an outer surface of the body and connected to the internal electrode, wherein the body includes: an active portion having the plurality of internal electrodes positioned therein to form a capacitance; a side edge portion formed by providing a dielectric layer and covering at least one of a first surface and a second surface of the effective portion that are opposite to each other in the second direction; and a covering portion formed by providing dielectric layers and covering the effective portion in the first direction, wherein each of the dielectric layers includes a barium titanate-based composition, the dielectric layer of the side edge portion includes tin (Sn), and a Sn content in the dielectric layer of the side edge portion is different from a Sn content in the dielectric layer of the effective portion with respect to 100 mol% of the barium titanate-based composition, and the dielectric layer of the side edge portion includes at least some crystal grains having a core-shell structure. Further, the Sn content in the dielectric layer of the covering part may be different from the Sn content in the dielectric layer of the side edge part with respect to 100 mol% of the barium titanate-based composition, and the dielectric layer of the covering part may include at least some crystal grains having a core-shell structure.
In the core-shell structure, the Sn content in the shell portion may be higher than the Sn content in the core.
The shell portion of the core-shell structure may include a barium titanate-based composition in which Ti may be substituted with Sn.
The side edge portion may include Sn in the dielectric layer at a higher content than Sn in the dielectric layer of the effective portion.
The shell portion of the core-shell structure may cover 30% or more of the external surface area of the core-shell structure.
In the dielectric layer of the side edge portion, grains in which the shell portion of the core-shell structure covers 30% or more of an outer surface area of the core-shell structure may be 10% or more of total grains.
The dielectric layer of the side edge portion may include 0.1mol to 10mol of Sn based on 100mol of barium titanate.
An average crystal grain size of crystal grains in the dielectric layer of the side edge portion may be smaller than an average crystal grain size of crystal grains in the dielectric layer of the effective portion.
The dielectric layer of the cover may include at least some grains having a core-shell structure, and in the core-shell structure, the Sn content in the shell portion may be higher than the Sn content in the core.
According to another aspect of the present disclosure, a multilayer capacitor may include: a body including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction with respective ones of the plurality of dielectric layers interposed therebetween; and an external electrode formed on an outer surface of the body and connected to the internal electrode, wherein the body includes: an active portion having the plurality of internal electrodes positioned therein to form a capacitance; a side edge portion including a plurality of dielectric layers and covering a first surface and a second surface of the effective portion that are opposite to each other in the second direction; and a cover including a plurality of dielectric layers and covering the effective part in the first direction, the dielectric layers including a barium titanate-based composition, the dielectric layers of the cover including Sn, and a content of Sn in the dielectric layers of the cover being different from a content of Sn in the dielectric layers of the effective part with respect to 100 mol% of the barium titanate-based composition, and the dielectric layers of the cover including at least some crystal grains having a core-shell structure. Further, the coating layer may have a Sn content in the dielectric layer different from a Sn content in the dielectric layer of the side edge portion with respect to 100 mol% of the barium titanate-based composition.
Drawings
The above and other aspects, features and advantages of the present disclosure will be more clearly understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, in which:
fig. 1 is a schematic perspective view showing an appearance of a multilayer capacitor according to an exemplary embodiment in the present disclosure;
FIG. 2 is a cross-sectional view taken along line I-I' of the multilayer capacitor of FIG. 1;
FIG. 3 is a cross-sectional view taken along line II-II' of the multilayer capacitor of FIG. 1;
FIG. 4 is a schematic enlarged view of a grain of the dielectric layer;
FIG. 5 is a diagram showing the body region of FIG. 3 in a subdivided state;
fig. 6 is a diagram showing a form of a dielectric crystal grain of an effective portion; and
fig. 7 is a diagram showing the form of dielectric grains of the side edge portion.
Detailed Description
Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic perspective view illustrating an appearance of a multilayer capacitor according to an exemplary embodiment in the present disclosure. Fig. 2 is a sectional view taken along line I-I' of the multilayer capacitor of fig. 1. Fig. 3 is a sectional view taken along line II-II' of the multilayer capacitor of fig. 1. Fig. 4 is a schematic enlarged view of the crystal grains of the dielectric layer. Fig. 5 is a diagram illustrating the body region of fig. 3 in a subdivided state.
Referring to fig. 1 to 3, a multilayer capacitor 100 according to an exemplary embodiment in the present disclosure may include: a body 110 including a dielectric layer 111 and a plurality of internal electrodes 121 and 122 stacked in a first direction (X direction), with the respective dielectric layers 111 interposed between the plurality of internal electrodes 121 and 122; and outer electrodes 131 and 132, wherein the body 110 includes: an effective portion 112 including a plurality of dielectric layers and a plurality of internal electrodes stacked with the dielectric layers interposed therebetween; a side edge portion 113 including a plurality of dielectric layers; and a cover 114 comprising a plurality of dielectric layers. Here, the dielectric layer 111 of the side edge portion 113 may include Sn, and the Sn content in the dielectric layer 111 of the side edge portion 113 may be different from the Sn content in the dielectric layer 111 of the effective portion 112. In addition, the dielectric layer 111 of the side edge portion 113 may include at least some crystal grains having a core-shell structure. Further, the Sn content in the dielectric layer of the side edge portion may be different from the Sn content in the dielectric layer of the covering portion with respect to 100 mol% of the barium titanate-based composition. In addition, the Sn content in the dielectric layer of the covering part may be different from the Sn content in the dielectric layer of the effective part, for example, the Sn content in the dielectric layer of the covering part may be higher than the Sn content in the dielectric layer of the effective part. The term "content" disclosed in the present specification may be a molar content or a molar concentration with respect to 100 mol% of an element of the barium titanate-based composition.
The body 110 may have a stacked structure in which a plurality of dielectric layers 111 are stacked in the first direction (X direction), and may be obtained by stacking, for example, a plurality of ceramic green sheets and then sintering. The plurality of dielectric layers 111 may have a form integrated with each other through such a sintering process. The body 110 may have a shape similar to a straight parallelepiped shape as shown in fig. 1. The dielectric layer 111 included in the body 110 may include a ceramic material having a high dielectric constant, and may include barium titanate (BaTiO)3) A base composition. Specifically, the dielectric layer 111 may include a base material main component including Ba and Ti. Here, the main component of the substrate may include BaTiO3Or (Ba, Ca) (Ti, Ca) O partially solid-dissolved with Ca, Zr, Sn, etc3、(Ba,Ca)(Ti,Zr)O3、Ba(Ti,Zr)O3Or (Ba, Ca) (Ti, Sn) O3The principal component of the representation. Further, if necessary, with a ceramic as a main componentTogether, the dielectric layer 111 may further include additives, organic solvents, plasticizers, binders, dispersants, and the like. Here, the additive may include a metal component, and may be added in the form of a metal oxide in the manufacturing process. Examples of such metal oxide additives can include MnO2、Dy2O3、BaO、MgO、Al2O3And Cr2O3At least one of (1). In addition, examples of the additive may further include SiO2And CaCO3At least one of (1).
Each of the plurality of internal electrodes 121 and 122 may be formed by printing a paste including a conductive metal of a predetermined thickness on one surface of the ceramic green sheet and then sintering. In this case, as shown in fig. 2, the plurality of internal electrodes 121 and 122 may include first and second internal electrodes 121 and 122, the first and second internal electrodes 121 and 122 being exposed to surfaces of the body 110 that are opposite to each other in the third direction (Z direction), respectively. Here, the third direction (Z direction) may be a direction perpendicular to the first direction (X direction) and the second direction (Y direction). Here, the second direction (Y direction) refers to a direction in which the first surface S1 and the second surface S2 of the effective part 112 of the main body 110 are opposite to each other. In this case, the first and second internal electrodes 121 and 122 may be connected to different external electrodes 131 and 132, respectively, to have different polarities when the multilayer capacitor is driven, and may be electrically separated from each other by respective dielectric layers 111 disposed between the first and second internal electrodes 121 and 122. However, according to another exemplary embodiment, the number of the outer electrodes 131 and 132 and the connection manner between the outer electrodes 131 and 132 and the inner electrodes 121 and 122 may vary. Examples of the main material constituting the internal electrodes 121 and 122 may include nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), or an alloy thereof, and the like.
The external electrodes 131 and 132 may include first and second external electrodes 131 and 132 formed on the outer surface of the body 110 and connected to the first and second internal electrodes 121 and 122, respectively. The external electrodes 131 and 132 may be formed by a method of preparing a material including a conductive metal in a paste form and then applying the paste to the body 110, and examples of the conductive metal may include nickel (Ni), copper (Cu), palladium (Pd), gold (Au), or an alloy thereof. The external electrodes 131 and 132 may further include a plating layer containing Ni, Sn, or the like.
Referring to fig. 3, the active portion 112 may have a plurality of internal electrodes 121 and 122 positioned therein to form a capacitance. The side edge portion 113 may cover at least one of the first surface S1 and the second surface S2 of the effective portion 112 that are opposite to each other in the second direction (Y direction), and in the present exemplary embodiment, the side edge portion 113 has been shown to cover both the first surface S1 and the second surface S2 of the effective portion 112. In this case, the second direction (Y direction) may be perpendicular to the first direction (X direction). The covering portion 114 may cover the effective portion 112 in the first direction (X direction), and in the present exemplary embodiment, the covering portion 114 may be disposed on both an upper surface and a lower surface of the effective portion 112 in the first direction (X direction).
In the present exemplary embodiment, the moisture-proof property, toughness, and the like are improved by adjusting the composition, grain size, and the like of the dielectric layer 111 in the side edge portion 113 that has a large influence on the reliability of the multilayer capacitor 100. The following description will be provided based on the side edge portion 113, but the dielectric layer 111 having excellent reliability may be applied to the covering portion 114, or may be applied to both the side edge portion 113 and the covering portion 114, to significantly increase the characteristic improvement.
In the present exemplary embodiment, the dielectric layer 111 of the effective part 112 and the dielectric layer 111 of the side edge part 113 may include Sn, but the Sn content in the dielectric layer 111 of the effective part 112 and the Sn content in the dielectric layer 111 of the side edge part 113 may be different from each other. According to the research of the present inventors, it has been confirmed that grain growth characteristics, toughness, and the like are changed according to the Sn content in the dielectric layer 111 including the barium titanate-based composition, and electrical characteristics, mechanical characteristics, and the like are improved by making the Sn content of each region constituting the body 110 different from each other. As an example, the Sn content included in the dielectric layer 111 of the side edge portion 113 may be higher than the Sn content included in the dielectric layer 111 of the effective portion 112. Accordingly, moisture-proof characteristics, toughness, and the like of the body 110 may be improved.
The dielectric layer 111 of the side edge portion 113 may include Sn to improve moisture-proof reliability and have impact resistance and crack resistance, and the Sn content in the dielectric layer 111 of the side edge portion 113 may be adjusted to be higher than the Sn content in the dielectric layer 111 of the effective portion 112. In this case, the dielectric layer 111 of the effective part 112 may not include Sn, or may include only a very small amount of Sn even though it includes Sn. When the Sn content included in the dielectric layer 111 of the side margin portion 113 is higher than the Sn content included in the dielectric layer 111 of the effective portion 112, the grain growth of the crystal grains in the dielectric layer 111 of the side margin portion 113 may not be relatively large, so that the average grain size of the crystal grains included in the dielectric layer 111 of the side margin portion 113 may be adjusted to be smaller than the average grain size of the crystal grains included in the dielectric layer 111 of the effective portion 112. Therefore, the moisture-proof property and toughness of the side edge portion 113 can be higher than those of the effective portion 112. Therefore, when the multilayer capacitor 100 is mounted on a circuit board or the like, cracks in the main body 110 (particularly the side edge portion 113) can be suppressed.
The Sn content may be adjusted to exhibit a sufficient level of improved characteristics in the side edge portion 113. In this case, based on 100mol of barium titanate (BaTiO)3) The dielectric layer 111 of the side edge portion 113 may contain 0.1mol to 10mol of Sn. When based on 100mol of barium titanate (BaTiO)3) When the content of Sn included in the dielectric layer of the side edge portion is less than 0.1mol, it may be difficult to exhibit a significant effect by adding Sn, and when the content of Sn exceeds 10mol based on 100mol of barium titanate, there may be a problem in that impact resistance is deteriorated due to network formation between Sn and Sn.
In the present exemplary embodiment, as shown in fig. 4, the dielectric layer 111 of the side edge portion 113 may include crystal grains 11 having a core-shell structure and crystal grains 12 having no core-shell structure. In this case, in the core-shell structure, the Sn content in the shell portion 11b may be higher than that in the core 11a, and the shell portion 11b may have a form in which some of Ti is substituted with Sn, that is, the shell portion 11b may include a barium titanate-based composition in which Ti is substituted with Sn. The shell portion 11b may cover 30% or more of the outer surface area of the core 11 a. In addition, the dielectric layer 111 of the side edge portion 113 includes crystal grains 11 in an amount of 10% or more relative to the total number of crystal grains 11 and 12 included in the dielectric layer 111 of the side edge portion, and the shell portion 11b covers 30% or more of the outer surface area of the core 11 a. Further, the thickness of the shell portion 11b is not particularly limited, and may be, for example, 2nm to 50 nm. The thickness of the shell portion 11b can be measured by a method using a Transmission Electron Microscope (TEM) and an energy dispersive X-ray spectrometer (EDS) apparatus. Specifically, TEM-EDS line analysis may be performed on a long axis passing through the center of the core-double shell structure of the crystalline grain. The strength of the core-double shell structure is then measured, which may be proportional to the Sn concentration. The boundary between the core and the shell of the crystal grain can be determined by detecting a portion where the Sn concentration is significantly increased.
Sn may be an element having the same oxidation number as that of Ti, the ionic radius of Sn is different from that of Ti, and when barium titanate (BaTiO) in the shell portion 11b3) When some of Ti of the base composition is substituted with Sn, a structure generally having a cubic phase may be converted into a lattice structure and into a phase having a dipole moment, so that the dielectric constant of the shell portion 11b itself may be increased to ensure a high dielectric constant. In addition, when some of Ti in the shell portion 11b is substituted by Sn, the ratio of Ba to Ti (Ba/Ti) may be increased, so that grain growth of the dielectric crystal grains may be suppressed. In this case, the ratio of Ba to Ti (Ba/Ti) may be greater than or equal to 1.0150. When the ratio of Ba to Ti (Ba/Ti) is greater than or equal to 1.0150 such that Ba has a high molar ratio, grain growth of the dielectric grains at sintering can be suppressed, so that the dielectric grains can be compacted. Therefore, electrical characteristics (breakdown voltage characteristics), moisture resistance reliability, and the like can be improved.
As described above, the average grain size of the crystal grains G2 (see fig. 7) included in the dielectric layer 111 of the side edge portion 113 may be smaller than the average grain size of the crystal grains G1 (see fig. 6) included in the dielectric layer 111 of the effective portion 112, and the Sn content in the dielectric layer 111 of the side edge portion 113 is relatively higher than the Sn content in the dielectric layer 111 of the effective portion 112. For example, the average grain size of the grains included in the dielectric layer 111 of the side edge portion 113 may be 100nm to 700 nm. Further, the dielectric layer 111 of the effective part 112 may include a composition generally used in the field of multilayer ceramic capacitors (MLCCs), in which case the average grain size of grains included in the dielectric layer 111 of the effective part 112 may be 300nm to 900 nm. In this case, as the Sn content included in the dielectric layer 111 of the side edge portion 113 increases, the grain size may decrease from the outer boundary surface of the side edge portion 113 toward the inner region adjacent to the effective portion 112. That is, Sn in the side edge portion 113 may reduce the grain size of the dielectric crystal grain, and the grain size of the dielectric crystal grain may be further reduced at the inner side of the side edge portion 113 adjacent to the effective portion 112, and therefore, the side edge portion 113 may have high toughness.
The average grain size of the grains included in the dielectric layer 111 may be obtained by a method of calculating a circle-equivalent diameter of the dielectric grains extracted from the corresponding region, a method of measuring a length of a long axis and a length of a short axis of the dielectric grains to calculate an average grain size, and the like. Referring to fig. 6 and 7 and fig. 5, as an example of a method of measuring the grain size, the average grain size of the grains included in the dielectric layer 111 may be measured based on a cutting plane cut in the first direction (X direction) and the second direction (Y direction). In this case, a direction perpendicular to a surface cut at the center of the body 110 in the length direction may be used as the third direction (Z direction).
When the length of the main body 110 in the first direction (X direction) is T and the length of the effective part 112 in the second direction (Y direction) is WA, the average grain size of the grains included in the dielectric layer 111 of the effective part 112 may be measured from the size of the grains G1 present in the first rectangle R1 in the cutting plane of fig. 5. The first rectangle R1 may include the central area CA of the active portion 112 and have a horizontal length of WA/3 and a vertical length of T/3. In addition, the first rectangle R1 may be symmetrical with respect to the center lines L1 and L2 of the effective part 112 in the first and second directions. The average grain size of the crystal grains included in the dielectric layer 111 of the side edge portion 113 may be measured from the size of the crystal grains G2 existing in the second rectangle R2 including the central region CM. When the length of the side edge portion 113 in the second direction (Y direction) is WM, the second rectangle R2 may have a horizontal length of WM/3 and a vertical length of T/3, and may be symmetrical with respect to center lines L3 and L2 of the side edge portion 113 in the first and second directions. In a similar manner, the average grain size of the grains included in the dielectric layer 111 of the covering portion 114 can be obtained by measuring the size of the grains existing in the third rectangle R3 including the central region CC. Here, the grains may have a form as shown in fig. 7. The third rectangle R3 may have a horizontal length of WA/3 and a vertical length of t/2 (where t is the thickness of the cover 114), and may be symmetrical with respect to a center line of the cover 114 in the first and second directions.
As described above, in the case of measuring the sizes of the crystal grains G1 and G2, a method of measuring the areas of the crystal grains G1 and G2 and converting the measured areas into circle-equivalent diameters, a method of measuring the lengths of the major axes and the minor axes of the crystal grains G1 and G2 to calculate the average crystal grain size, or the like can be used. In addition, in order to improve the accuracy of measurement, only the crystal grains G1 and G2 whose entire regions are surrounded by grain boundaries in the reference rectangles R1, R2, and R3 may be selected.
In addition, the description of the dielectric layer 111 of the side edge portion 113 may be applied to the covering portion 114 as it is, and the above-described Sn content characteristic in the dielectric layer 111 and the core-shell structure of the dielectric layer 111 may be applied only to the side edge portion 113 and not to the covering portion 114. Alternatively, the Sn content characteristic in the dielectric layer 111 and the core-shell structure of the dielectric layer 111 described above may be applied to both the side edge portion 113 and the covering portion 114.
As described above, according to the exemplary embodiments in the present disclosure, the electrical and mechanical characteristics of the multilayer capacitor may be improved.
While exemplary embodiments have been shown and described above, it will be readily understood by those skilled in the art that modifications and variations may be made without departing from the scope of the invention as defined by the appended claims.

Claims (26)

1. A multilayer capacitor, comprising:
a body including an effective portion including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction with respective ones of the plurality of dielectric layers interposed therebetween; and
an external electrode formed on an outer surface of the body and connected to the internal electrode,
wherein the main body includes: the active portion having the plurality of internal electrodes positioned therein to form a capacitance; a side edge portion covering at least one of a first surface and a second surface of the effective portion that are opposite to each other in the second direction; and a covering portion covering the effective portion in the first direction,
the dielectric layers of the active portion, the side edge portions and the cover portion comprise a barium titanate-based composition,
the dielectric layer of the side edge portion includes Sn, and a Sn content in the dielectric layer of the side edge portion is different from that in the dielectric layer of the effective portion with respect to 100 mol% of the barium titanate-based composition, and
the dielectric layer of the side edge portion includes a plurality of crystal grains having a core-shell structure.
2. The multilayer capacitor of claim 1, wherein in the core-shell structure, the Sn content in the shell portion is higher than the Sn content in the core.
3. The multilayer capacitor of claim 1, wherein the shell portion of the core-shell structure comprises a barium titanate-based composition having Ti substituted with Sn.
4. The multilayer capacitor as claimed in claim 1, wherein the Sn content in the dielectric layer of the side edge portion is higher than the Sn content in the dielectric layer of the effective portion.
5. The multilayer capacitor of claim 1, wherein the shell portion of the core-shell structure covers 30% or more of the outer surface area of the core-shell structure.
6. The multilayer capacitor of claim 1, wherein the dielectric layer of the side edge portion comprises grains in an amount of 10% or more relative to a total number of grains in the dielectric layer of the side edge portion and the shell portion of the core-shell structure covers 30% or more of an outer surface area of the core-shell structure.
7. The multilayer capacitor as claimed in claim 1, wherein based on 100mol of BaTiO3The dielectric layer of the side edge portion includes 0.1mol to 10mol of Sn.
8. The multilayer capacitor as claimed in claim 1, wherein an average crystal grain size of crystal grains in the dielectric layer of the side edge portion is smaller than an average crystal grain size of crystal grains in the dielectric layer of the effective portion.
9. The multilayer capacitor as claimed in claim 8, wherein the average crystal grain size of crystal grains in the dielectric layers of the side edge portion is 100nm to 700nm, and the average crystal grain size of crystal grains in the dielectric layers of the effective portion is 300nm to 900 nm.
10. The multilayer capacitor of claim 1, wherein the dielectric layer of the cover comprises at least some grains having a core-shell structure, and in the core-shell structure, the Sn content in the shell portion is higher than the Sn content in the core.
11. The multilayer capacitor of claim 1, wherein the Sn content in the shell portion is a molar concentration of Sn relative to 100 mol% of the barium titanate-based composition.
12. A multilayer capacitor, comprising:
a body including an effective portion including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction with respective ones of the plurality of dielectric layers interposed therebetween; and
an external electrode formed on an outer surface of the body and connected to the internal electrode,
wherein the main body includes: the active portion having the plurality of internal electrodes positioned therein to form a capacitance; a side edge portion including a plurality of dielectric layers and covering a first surface and a second surface of the effective portion that are opposite to each other in the second direction; and a covering portion including a plurality of dielectric layers and covering the effective portion in the first direction,
the dielectric layers of the active portion, the side edge portions, and the cover portion comprise a barium titanate-based composition,
the dielectric layer of the covering portion includes Sn, and a Sn content in the dielectric layer of the covering portion is different from a Sn content in the dielectric layer of the effective portion with respect to 100 mol% of the barium titanate-based composition, and
the dielectric layer of the cover includes a plurality of grains having a core-shell structure.
13. The multilayer capacitor of claim 12, wherein in the core-shell structure, the Sn content in the shell portion is higher than the Sn content in the core.
14. The multilayer capacitor of claim 12, wherein the shell portion of the core-shell structure comprises a barium titanate-based composition having Ti substituted with Sn.
15. The multilayer capacitor of claim 12, wherein the Sn content in the dielectric layers of the cover portion is higher than the Sn content in the dielectric layers of the active portion.
16. The multilayer capacitor of claim 12, wherein the shell portion of the core-shell structure covers 30% or more of the outer surface area of the core-shell structure.
17. The multilayer capacitor of claim 12, wherein the dielectric layer of the cover comprises grains in an amount of 10% or more relative to a total number of grains in the dielectric layer of the cover and the shell portion of the core-shell structure covers 30% or more of an external surface area of a core of the core-shell structure.
18. The multilayer capacitor of claim 12, based on 100mol of BaTiO3The dielectric layer of the covering part comprises 0.1mol to 10mol of Sn.
19. The multilayer capacitor of claim 12, wherein an average grain size of the grains in the dielectric layers of the cover portion is smaller than an average grain size of the grains in the dielectric layers of the active portion.
20. The multilayer capacitor as claimed in claim 12, wherein based on 100mol of BaTiO3The dielectric layer of the covering part comprises 0.1mol to 10mol of Sn.
21. A multilayer capacitor, comprising:
a body including an effective portion including a plurality of dielectric layers and a plurality of internal electrodes stacked in a first direction with respective ones of the plurality of dielectric layers interposed therebetween; and
an external electrode formed on an outer surface of the body and connected to the internal electrode,
wherein the main body includes: the active portion having the plurality of internal electrodes positioned therein to form a capacitance; a side edge portion including a plurality of dielectric layers and covering at least one of first and second surfaces of the effective portion that are opposite to each other in the second direction; and a covering portion including a plurality of dielectric layers and covering the effective portion in the first direction,
the dielectric layers of the active portion, the side edge portions, and the cover portion comprise a barium titanate-based composition,
the dielectric layers of the covering portion and the side edge portions include Sn, and a Sn content in the dielectric layers of the covering portion is different from a Sn content in the dielectric layers of the side edge portions with respect to 100 mol% of the barium titanate-based composition.
22. The multilayer capacitor of claim 21 wherein the dielectric layers of the cover comprise at least some grains having a core-shell structure.
23. The multilayer capacitor of claim 22, wherein the shell portion of the core-shell structure covers 30% or more of the outer surface area of the core-shell structure.
24. The multilayer capacitor of claim 21, wherein the dielectric layers of the side edge portions include at least some grains having a core-shell structure.
25. The multilayer capacitor of claim 24, wherein the shell portion of the core-shell structure covers 30% or more of the outer surface area of the core-shell structure.
26. The multilayer capacitor of claim 21, wherein based on 100mol of BaTiO3The dielectric layer of the covering part comprises 0.1mol to 10mol of Sn.
CN202111293389.XA 2020-11-04 2021-11-03 Multilayer capacitor Pending CN114446660A (en)

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